/*
 * Copyright (c) 2009, Hamish Morgan. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the University of Sussex nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package locusts.server.physics;

import locusts.common.entities.Entity;

/**
 *
 * @author Hamish Morgan
 */
public class TranslateJoint implements Joint {

    private static final double MIN_DISTANCE = 1f;
    //
    protected final Entity A;
    protected final Entity B;
    protected double Ax;
    protected double Ay;
    protected double Bx;
    protected double By;

    public TranslateJoint(Entity a, Entity b, double ax, double ay, double bx,
            double by) {
        this.A = a;
        this.B = b;
        this.Ax = ax - a.getX();
        this.Ay = ay - a.getY();
        this.Bx = bx - b.getX();
        this.By = by - b.getY();
    }

    public TranslateJoint(Entity a, Entity b, double x, double y) {
        this(a, b, x, y, x, y);
    }

    public TranslateJoint(Entity a, Entity b) {
        this(a, b, a.getX(), a.getY(), b.getY(), b.getY());
    }

    protected TranslateJoint(TranslateJoint other) {
        this.A = other.A;
        this.B = other.B;
        this.Ax = other.Ax;
        this.Ay = other.Ay;
        this.Bx = other.Bx;
        this.By = other.By;
    }

    public Entity getEntityA() {
        return A;
    }

    public Entity getEntityB() {
        return B;
    }

    public void update(double period) {

        // that point of contact for moving
        final double Ox = A.getX() + Ax;
        final double Oy = A.getY() + Ay;

        // the target for the point of contact
        final double Tx = B.getX() + Bx;
        final double Ty = B.getY() + By;

        // If it hasn't moved much then don't bother.
        final double dx = Tx - Ox;
        final double dy = Ty - Oy;
        if (dx * dx + dy * dy <= MIN_DISTANCE * MIN_DISTANCE)
            return;

        A.setX(A.getX() - Ox + Tx);
        A.setY(A.getY() - Oy + Ty);

        Ax = Tx - A.getX();
        Ay = Ty - A.getY();

        A.setModified();
        
    }

    @Override
    public TranslateJoint clone() {
        return new TranslateJoint(this);
    }
}

